Manufacturing method of semiconductor device and manufacturing method of lead frame

ABSTRACT

Improvement in the reliability of a semiconductor device is aimed at. By heating a lead frame, after preparing a lead frame with a tape, until a resin molding is performed, at the temperature 160 to 300° C. (preferably 180 to 300° C.) for a total of more than 2 minutes in the atmosphere which has oxygen, crosslinkage density becoming high in resin of adhesives, a low molecular compound volatilizes and jumps out outside, therefore as a result, since a low molecular compound does not remain in resin of adhesives, the generation of copper migration can be prevented.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.11/181,929, filed Jul. 15, 2005. The present application claims priorityfrom Japanese patent application No. 2004-209376 filed on Jul. 16, 2004,the contents of which are hereby incorporated by reference into thisapplication.

1. FIELD OF THE INVENTION

This invention relates to a semiconductor manufacturing technology, andparticularly relates to an effective technology in the application toimprovement in the reliability of the semiconductor device using a tape.

2. DESCRIPTION OF THE BACKGROUND ART

In the conventional semiconductor device using a tape and itsmanufacturing method, in order to seal a semiconductor chip, in the casewhere an insulating tape layer is adhered to the leads of a lead frame,or to the metal printed wirings of a tab through an adhesion materiallayer, the adhesion material layer is formed existing on the leads ormetal printed wirings, and not existing in the insulating tape layersurface between the leads of the plurality of leads, or between theplurality of metal printed wirings (for example, refer to PatentReference 1).

In the conventional semiconductor device using a tape and itsmanufacturing method, the surface of the leads made of Cu is covered bythe metal plating of about 30 micrometers thick of gold, platinum,palladium, indium, chromium, titanium, antimony, rhodium, tantalum andvanadium, the alloy containing such metal, Ag which metal ion cannotmove into adhesives, etc. The insulating tape with which adhesives wereapplied is stuck on a lead via the protective film by metal plating. Themetal plating is performed only to the surface of the lead of the tapingposition on which insulating tape is stuck (for example, refer to PatentReference 2).

[Patent Reference 1] Japanese Unexamined Patent Publication No. Hei 9(1997)-153587(FIG. 1)

[Patent Reference 2] Japanese Unexamined Patent Publication No. Hei 10(1998)-163410(FIG. 1)

SUMMARY OF THE INVENTION

Mainly in the semiconductor device with many pins among semiconductordevices, the semiconductor package of structure which stuck a tape forfixation on inner leads in order to stop deformation and disturbance ofthe inner leads is known.

In the semiconductor device using a tape, if the lead is formed of thecopper alloy, the copper migration phenomenon in which the copperionized from the lead side of plus potential jumps out, this copper ionmoves the layer of adhesives and reaches the adjoining lead of minuspotential, and the copper deposits from the lead side of this minuspotential, occurs.

In the adhesives, the carbonyl group which exists in them performs hightemperature oxidization, a carboxyl group is formed, and this carboxylgroup performs complex formation and makes copper ionize. That is, thecarbonyl group compound in the adhesives is promoting the reaction.

If copper migration grows at a lead side of minus potential, finally thecopper will be connected between adjoining leads, and causing defectivelead leak will pose a problem.

These inventors found out that, as a result of examining the heattreatment method as a method of controlling migration, the baking in theair worked effectively in out-gas processing, and the effect whichcontrols generation of migration was very high. These inventors foundout that not only ionicity impurities but existence of the low molecularcompound (volatilization ingredients, such as a solvent) slightlycontained in resin of adhesives reduced the migration-proofcharacteristic remarkably. The following things can be considered asgeneration factors by the low molecular compound.

1. Plasticization of base resin by a low molecular compound(volatilization ingredients, such as a solvent), which reduces theelastic modulus of base resin and increases the degree of ion migration.

2. Swelling of base resin by a low molecular compound (volatilizationingredients, such as a solvent), which makes the free volume between themolecules in base resin increase, and increases the degree of ionmigration.

3. Carrier action of copper ion, which takes solvation structure andincreases the degree of ion migration.

As that to which the migration-proof characteristic is reduced as a lowmolecular compound (volatilization ingredients, such as a solvent), theexistence of a ketone system compound with high solubility and solvationability is the largest in influence, and subsequently existence of analcoholic system compound has a bad influence. It became clear thatusually, although most low molecular compounds volatilize by heattreatment of a process, the alcoholic system compound in which a boilingpoint is higher than a ketone system compound remains easily slightly,and existence of few alcoholic system compound, especially methanol of alow molecular weight which remained reduces the migration-proofcharacteristic remarkably.

The Patent Reference 1 (Japanese Unexamined Patent Publication No. Hei 9(1997)-153587) has the indication of preventing migration by havingcomposition which does not provide an adhesion material layer betweenleads. The Patent Reference 2 (Japanese Unexamined Patent PublicationNo. Hei 10 (1998)-163410) has the indication of preventing migration byhaving composition which gave plating by the metal through which ioncannot move the inside of adhesives on the surface of the copper lead.However, both the Patent Reference 1 and the Patent Reference 2 have nodescription of preventing migration by flying outside the low molecularcompound contained in adhesives by heat treatment.

The purpose of this invention is to offer a method of manufacturing asemiconductor device and a method of manufacturing a lead frame whichcan aim at improvement in reliability.

The purposes and the new features of above and others of this inventionwill become clear from the description and the accompanying drawings ofthis specification.

It will be as follows if the outline of a typical thing is brieflyexplained among inventions indicated in a present application.

According to one aspect of the present invention, a manufacturing methodof a semiconductor device comprises the steps of: preparing the leadframe over which a tape was stuck via adhesives containing a lowmolecular compound; connecting a part of the lead frame and asemiconductor chip; connecting electrically the leads of the lead frameand the semiconductor chip; and performing resin molding of thesemiconductor chip; wherein after sticking the tape over the lead frameand before performing the resin molding, the lead frame is heated at atemperature of 180 to 300° C. for a total of more than 2 minutes in anatmosphere which has oxygen.

According to another aspect of the present invention, a lead frame overwhich a tape was stuck via adhesives containing a low molecular compoundis prepared; and after sticking the tape over the lead frame and beforeperforming a resin molding, the lead frame is heated at a temperature of180 to 300° C. for a total of more than 2 minutes in an atmosphere whichhas oxygen.

According to other aspect of the present invention, a lead frame overwhich a tape was stuck via adhesives containing a low molecular compoundis prepared; and after sticking the tape over the lead frame and beforeperforming a resin molding, the lead frame is heated with 160°C.≦heating temperature≦300° C. and a heating total time>2 minutes, in anatmosphere which has oxygen.

According to other aspect of the present invention, a lead frame overwhich a tape was stuck via adhesives containing a low molecular compoundis prepared; and after sticking the tape over the lead frame and beforeperforming a resin molding, the lead frame is heated at a temperature of180 to 300° C. for a total of more than 2 minutes in a gas atmospherewhich lowers an activation energy of a reaction of a molecule.

According to other aspect of the present invention, in a manufacturingmethod of a semiconductor device using a member over which substrate aconductor part which includes copper or a copper alloy was stuck viathermosetting adhesives, before performing a resin molding, the memberis heated at a temperature of 180 to 300° C. for a total of more than 2minutes in an atmosphere which has oxygen.

According to other aspect of the present invention, a manufacturingmethod of a lead frame comprises the steps of: sticking a tape viaadhesives which contain a low molecular compound over a lead frame whichhas a plurality of leads; after sticking the tape, heating the leadframe at a temperature of 180 to 300° C. for a total of more than 2minutes in an atmosphere which has oxygen; and shipping the lead frame.

It will be as follows if the effect acquired by the typical thing amonginventions indicated in a present application is explained briefly.

By heating a lead frame, after sticking a tape on a lead frame andbefore performing a resin molding, at the temperature of 180 to 300° C.for a total of more than 2 minutes in the atmosphere which has oxygen,the hardening reaction accompanied by the oxidization crosslinkage inresin of adhesives can be promoted, and crosslinkage density becominghigh, a low molecular compound volatilizes and jumps out outside.Thereby, since a low molecular compound does not remain in resin ofadhesives, the generation of migration can be prevented. As a result,improvement in the reliability of a semiconductor device can be aimedat.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A to 1C are mimetic diagrams showing an example of each state ofthe crosslinking reaction of resin of the adhesives of a tape in themanufacturing method of the semiconductor device of Embodiment 1 of thisinvention, and the crosslinking reaction of resin of the adhesives of acomparative example;

FIG. 2 is a data diagram showing an example of the general solubilityparameter (SP value) contained in adhesives;

FIG. 3 is a mimetic diagram showing an example of normal chaincombination of a molecule;

FIG. 4 is a mimetic diagram showing an example of three-dimensionalcombination of a molecule;

FIG. 5 is a flow diagram showing an example of the assembly procedurewith the manufacturing method of the semiconductor device of Embodiment1 of this invention;

FIG. 6 is a flow diagram showing the assembly procedure of themanufacturing method of the semiconductor device of a comparativeexample;

FIG. 7 is a fragmentary sectional view showing an example of thestructure of the tape used in the manufacturing method of thesemiconductor device of Embodiment 1 of this invention;

FIG. 8 is a partial plan view showing an example of the structure of alead frame used in the manufacturing method of the semiconductor deviceof Embodiment 1 of this invention;

FIG. 9 is a partial plan view showing an example of the structure afterthe die bonding in the manufacturing method of the semiconductor deviceof Embodiment 1 of this invention;

FIG. 10 is a partial plan view showing an example of the structure afterthe wire bonding in the manufacturing method of the semiconductor deviceof Embodiment 1 of this invention;

FIG. 11 is a partial plan view showing an example of the structure afterthe resin molding in the manufacturing method of the semiconductordevice of Embodiment 1 of this invention;

FIG. 12 is a sectional view showing an example of the structure in eachstep till the wire bonding in the manufacturing method of thesemiconductor device of Embodiment 1 of this invention;

FIG. 13 is a sectional view showing an example of the structure afterthe resin molding and after the cut formation in the manufacturingmethod of the semiconductor device of Embodiment 1 of this invention;

FIG. 14 is a sectional view showing the structure of the semiconductordevice of a modification assembled with the manufacturing method of thesemiconductor device of Embodiment 1 of this invention;

FIG. 15 is a plan view showing the structure of the semiconductor deviceshown in FIG. 14;

FIG. 16 is a partial plan view showing the structure of thesemiconductor device of a modification assembled with the manufacturingmethod of the semiconductor device of Embodiment 1 of this invention;

FIG. 17 is a fragmentary sectional view showing the structure of thesemiconductor device shown in FIG. 16;

FIG. 18 is a flow diagram showing an example of the procedure of themanufacturing method of the lead frame of Embodiment 2 of thisinvention;

FIG. 19 is a partial plan view showing an example of the structure ofthe frame after etching in the assembly of the lead frame shown in FIG.18;

FIG. 20 is a partial plan view showing an example of the structure ofthe frame after partial silver plating formation in the assembly of thelead frame shown in FIG. 18; and

FIG. 21 is a partial plan view showing an example of the structure ofthe frame after taping in the assembly of the lead frame shown in FIG.18.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following embodiments, except for the time when particularlyrequired, explanation of the same or same portion is not repeated inprinciple.

Although it divides and explains to a plurality of sections orembodiments by the following embodiments when there is the necessity forconvenience, except for the case where it shows clearly especially, theyare not mutually unrelated and one side has relation, such as amodification, details, supplementary explanation, etc. of a part or allof another side.

In cases where the number of elements (the number, a numerical value,quantity, the range, etc. are included) etc. is mentioned in thefollowing embodiments, except for the case where it shows clearlyespecially and for the case where it is theoretically limited to aspecific number clearly etc., they shall be not the thing limited to thespecific number but more than the specific number, or less.

Hereafter, the embodiments of this invention are explained in detailbased on the drawings. In the all diagrams for explaining embodiments,the same mark is given to the member which has the same function, andexplanation of the repetition is omitted.

Embodiment 1

FIGS. 1A to 1C are mimetic diagrams showing an example of each state ofthe crosslinking reaction of resin of the adhesives of a tape in themanufacturing method of the semiconductor device of Embodiment 1 of thisinvention, and the crosslinking reaction of resin of the adhesives of acomparative example; FIG. 2 is a data diagram showing an example of thegeneral solubility parameter (SP value) contained in adhesives; FIG. 3is a mimetic diagram showing an example of normal chain combination of amolecule; FIG. 4 is a mimetic diagram showing an example ofthree-dimensional combination of a molecule; FIG. 5 is a flow diagramshowing an example of the assembly procedure with the manufacturingmethod of the semiconductor device of Embodiment 1 of this invention;FIG. 6 is a flow diagram showing the assembly procedure of themanufacturing method of the semiconductor device of a comparativeexample; FIG. 7 is a fragmentary sectional view showing an example ofthe structure of the tape used in the manufacturing method of thesemiconductor device of Embodiment 1 of this invention; FIG. 8 is apartial plan view showing an example of the structure of a lead frameused in the manufacturing method of the semiconductor device ofEmbodiment 1 of this invention; FIG. 9 is a partial plan view showing anexample of the structure after the die bonding; FIG. 10 is a partialplan view showing an example of the structure after the wire bonding;FIG. 11 is a partial plan view showing an example of the structure afterthe resin molding; FIG. 12 is a sectional view showing an example of thestructure in each step till the wire bonding; FIG. 13 is a sectionalview showing an example of the structure after the resin molding andafter the cut formation; FIG. 14 is a sectional view showing thestructure of the semiconductor device of a modification; FIG. 15 is aplan view of the semiconductor device shown in FIG. 14; FIG. 16 is apartial plan view showing the structure of the semiconductor device of amodification; and FIG. 17 is a fragmentary sectional view showing thestructure of the semiconductor device shown in FIG. 16.

This Embodiment 1 explains the manufacturing method of a semiconductordevice assembled using the lead frame on which the tape was stuck, and,preventing the generation of the copper migration in the semiconductordevice, aims at improvement in the reliability of the semiconductordevice.

That is, the manufacturing method of the semiconductor device of thisEmbodiment 1, prevents the generation of copper migration by heating alead frame 3 in the atmosphere which has oxygen at a predeterminedtemperature and beyond predetermined time, after sticking a tape 1 onlead frame 3 and before performing a plastic molding, when assembling asemiconductor device using lead frame 3 on which tape 1 was stuck viaadhesives 1 a containing low molecular compound 1 c. Since it cannot bemade to volatilize when heating and volatilizing low molecular compound1 c from adhesives 1 a if the circumference of adhesives 1 a issurrounded by resin for sealing, by the time when a resin molding isperformed, lead frame 3 is heated.

The case where adhesives 1 a are thermosetting adhesives, low molecularcompound 1 c contained in adhesives 1 a is acetaldehyde, methanol, oracetone, for example, and lead frame 3 is formed of copper or a copperalloy, is taken up, mentioned and explained as an example.

Tape 1 stops disturbance of an inner lead 3 a shown in FIG. 8, andprevents deformation, etc. of inner lead 3 a.

First, the mechanism which prevents copper migration by heat-treatinglead frame 3 on which tape 1 was stuck is explained.

Although low molecular compounds 1 c, such as methanol, are what isslightly contained in raw resin of adhesives 1 a without removingcompletely, in order to make it volatilize outside completely as outgas, it is necessary to change solubility parameters of phenol resin,etc. shown in FIG. 2 by raising the crosslinkage density of resin byperforming the hardening reaction by baking, and to press out themethanol whose solubility fell from the inside of resin.

Since it becomes a hardening reaction only by heating withoutoxidization by the baking in nitrogen (N2) atmosphere and by the bakingin vacuum atmosphere as shown in the comparative example of FIGS. 1A to1C in that case, as to crosslinkage 1 p, many normal chain structuresare formed and crosslinkage density does not fully go up (FIGS. 1A to1B), and a solubility parameter does not change to the grade whichvolatilizes low molecular compounds 1 c, such as methanol. As a result,low molecular compound 1 c remains in the resin (C of the comparativeexample of FIG. 1C).

On the other hand, in the baking in the atmosphere in the air etc. whichhas oxygen shown in Embodiment 1 of FIGS. 1A to 1C, in order that thereaction of oxidization crosslinkage 1 d may occur, sufficientcrosslinkage structure is easily formed in the inside of the resin(FIGS. 1A and 1C). By this, a solubility parameter can change andmethanol, i.e., low molecular compound 1 c, can be pressed out from theinside of the resin. As a result, low molecular compound 1 c does notremain in the resin (FIG. 1C).

Thus, it becomes possible by changing the solubility parameter of theresin by the baking in the air to remove low molecular compound 1 c (forexample, methanol) to which the migration-proof characteristic isreduced remarkably from adhesives 1 a.

As heat treatment conditions of the baking in the air, i.e., atmospherecontaining oxygen, (oxygen environment), it is thought that 160 to 300°C./2-minute-plus of a heating total time are enough. According to thecheck test, the test result that copper migration did not occur in caseswhere heat-treatment was performed for 5 minutes at 200° C. and for 3minutes at 240° C., respectively was obtained. In the manufacturingprocess of the semiconductor device using Cu lead frame with a fixedtape of a comparative example shown in FIG. 6, even if it applies a heathistory to lead frame 3 in the die bonding of Step S12 for 0.7 minute at225° C., and in the wire bonding of Step S13 for 0.8 minute at 240° C.,respectively, copper migration has occurred. Therefore, as a total timeto apply a heat history to lead frame 3, it is more than 2 minutes, andlet heating temperature in that case be the temperature of 160° C. ormore in consideration of a margin.

On the baking conditions in the high temperature of 300° C. or more, theembrittlement accompanied by the thermal decomposition reaction of anadhesives resin ingredient is caused conversely, a result in which itwill be in the state where the hard cladding layer is formed in thesurface, and gas cannot volatilize is brought, and it is not desirable.

Therefore, in the atmosphere which has oxygen, it becomes the processingconditions of 160 to 300° C./2 minute-plus of a heating total time, andpreferably, it is 180 to 300° C./more than 2 minutes of a heating totaltime, and the heat history on the assembling process of a semiconductordevice becomes appropriable for bake processing.

Next, the solubility parameter (SP value) shown in FIG. 2 is a numericalvalue about the polarity showing the ease of swelling of a molecule. Forexample, in cases where adhesives 1 a are mixed adhesives of phenolresin and bismaleimide resin, if the hardening reaction of phenol resinin adhesives is promoted by heat treatment, SP value of phenol resinwill fall from 11.3, and the difference from 14.5 of methanol willbecome large. If the difference of this SP value becomes large, methanolwill go away outside.

Next, the case where the mixed adhesives of phenol resin andbismaleimide resin are used is taken up as an example as adhesives 1 a.And the hardening reaction (three-dimensional crosslinking reaction) ofresin, and the drop of the activation energy of a reaction by containingoxygen in the atmosphere at the time of a reaction are explained.

Adhesives 1 a (phenol resin+bismaleimide resin) of tape 1 are in thesoft half-hardening state which contains an unreacted functional groupin large quantities where it is called B stage state, in the stage stuckon lead frame 3 shown in FIG. 8. When these unreacted functional groupsreact, macromolecule formation of B stage adhesives of a half-hardeningstate progresses.

The activation energy of the reaction which draws out hydrogen from apolymer molecule (what is called oxidation reaction) falls under oxygencontent atmosphere, and oxidation reaction of a polymer molecule occursfrequently also at a comparatively low temperature. Since adhesives 1 a(phenol resin+bismaleimide resin of a B stage state) of the descriptionin this Embodiment 1 contain the unreacted functional group in largequantities, it is easy to cause oxidation reaction.

Then, by heat-treating adhesives 1 a of this Embodiment 1 under oxygencontent atmosphere, a reactant functional group can be made into aperoxy radical by oxidization, and the crosslinking reaction(oxidization crosslinkage 1 d) which made this the starting point of thereaction is considered to progress easily. As a result, formation ofthree-dimensional structure and conjugated structure of an adhesivesresin ingredient as shown in FIG. 4 progresses. As the proof, the hue ofresin assumes the brown resulting from increase of electron transitionabsorption from the light yellow of B stage. When formation ofthree-dimensional structure progresses, sufficient crosslinkagestructure is easily formed in the inside of resin, the solubilityparameter can change, and low molecular compounds 1 c, such as methanol,can be pressed out from the inside of resin.

As compared with this, only the heat hardening reaction of adhesives 1 a(phenol resin+bismaleimide resin of a B stage state) occurs under theatmosphere which does not contain oxygen, such as nitrogen atmosphereand vacuum atmosphere. And the formation of the three-dimensionalstructure and conjugated structure of an adhesives resin ingredientaccompanying oxidation reaction as shown in FIG. 4 does not take place.And it is thought that the macromolecule formation with which the normalchain molecule became entangled as shown in FIG. 3 has occurredactively. The hue of resin is still the light yellow of B stage as theproof, and increases of electron transition absorption are hardlyobserved. Therefore, since sufficient crosslinkage structure is notformed in the inside of resin, a solubility parameter cannot fullychange, and low molecular compounds 1 c, such as methanol, cannot bepressed out from the inside of resin.

Next, the manufacturing method including heat treatment of lead frame 3of the semiconductor device of this Embodiment 1 is explained.

As shown in FIG. 5, a Cu lead frame with a fixed tape shown in Step S1is prepared first. That is, as shown in lead frame preparation of FIGS.8 and 12, along with inner lead 3 a sequence, lead frame 3 on which tape1 of the shape of a square ring was stuck on inner lead 3 a is prepared.In the lead frame 3, a tab 3 c which is a chip mounting part, hangingleads 3 d with which tab 3 c is supported in the four corner parts, aplurality of inner leads 3 a arranged around tab 3 c and a plurality ofouter leads 3 b which lead to each inner lead 3 a in one, respectivelyare formed.

Tape 1 prevents deformation of inner lead 3 a etc. stopping thedisturbance of inner lead 3 a, and as shown in FIG. 7, tape 1 includes alayer of adhesives 1 a, and a layer of base film 1 b. Base film 1 b is50 micrometers in thickness, and is formed from polyimide etc., forexample. Adhesives 1 a are mixed adhesives which are 50 micrometers inthickness and make phenol resin and bismaleimide resin the mainingredients, for example. Adhesives 1 a are also thermosettingadhesives, and low molecular compounds 1 c (impurities), such asmethanol, acetaldehyde, or acetone, are contained in these adhesives 1a.

Lead frame 3 includes copper or a copper alloy, for example. As shown inlead frame preparation of FIG. 12, silver plating 5 is formed at the tipof the surface of the surface side of each inner lead 3 a, namely of thewire connection side.

Then, in the manufacturing method of the semiconductor device of thisEmbodiment 1, the frame baking shown in Step S2 of FIG. 5, i.e., theheat treatment to lead frame 3 with tape 1, is performed. In that case,lead frame 3 is heated, in the atmosphere which has oxygen, at thetemperature of 180 to 300° C., for a total of more than 2 minutes. Forexample, in the inside of oxygen environment, lead frame 3 is heated atthe temperature of 240° C. for 2 to 5 minutes.

Thereby, as shown in FIG. 1B of Embodiment 1, the hardening reactionaccompanied by oxidization crosslinkage 1 d in resin of adhesives 1 acan be promoted. Crosslinkage density becoming high, low molecularcompound 1 c volatilizes and jumps out outside. That is, low molecularcompound 1 c can be pressed out outside from the inside of resin. As aresult, since low molecular compound 1 c leading to increase of thedegree of ion migration does not remain in resin of adhesives 1 a,movement of Cu ion between leads can be lost, therefore the generationof Cu migration can be prevented.

As a result, improvement in the reliability of a semiconductor devicecan be aimed at.

Improvement in the reliability of lead frame 3 on which tape 1 was stuckcan be aimed at.

As long as the atmosphere which heats lead frame 3 is the gas atmospherewhich can lower the activation energy of the reaction of a molecule,they may be gas atmosphere other than oxygen environment.

Although, as timing when heat-treatment of lead frame 3 with tape 1(frame baking) is performed, what is necessary is just to heat-treatbetween, before performing the molding (resin molding) of Step S5 ofFIG. 5, and after sticking tape 1 on lead frame 3, it is preferred toheat-treat even before the wire bonding of Step S4 of FIG. 5.

Since, after wire bonding, an alloy layer is formed when this connecteda gold ball, and a pad 4 c of aluminum of a semiconductor chip 4, and,if heat is applied to this, the alloy layer is spread, and it may cut inreliability examination and may result in the generation of a defectiveunit, cutting by the alloy layer can be prevented by heat-treating(frame baking) before wire bonding.

In heat-treating lead frame 3 with tape 1 (frame baking) also duringwire bonding, and after wire bonding unavoidably, as for the heattreatment time, it is preferred to distribute heat treatment time sothat it may become the total time of heat treatment before wirebonding>the total time of heat treatment during and after wire bonding.

Namely, since the desirable processing time of heat treatment of leadframe 3 with tape 1 (frame baking) is 2 to 5 minutes, and the time ofwire bonding is about 1.5 minutes, for example as shown in FIG. 5, bymaking it as the total time of heat treatment before wire bonding>thetotal time of heat treatment of during and after wire bonding, it is notnecessary to set up the time of wire bonding for a long time, and cancontrol that assembly time is prolonged.

Die bonding shown in Step S3 is performed after the end of heattreatment of Step S2 (frame baking) shown in FIG. 5. That is, as shownin die bonding of FIGS. 9 and 12, tab (part) 3 c of lead frame 3, and aback 4 b of semiconductor chip 4 are connected with silver paste(die-bonding material) 9.

Heat treatment of lead frame 3 with tape 1 (frame baking) may gotogether at the time of bake processing of silver paste 9 after diebonding of semiconductor chip 4 is performed with silver paste(die-bonding material) 9.

Wire bonding shown in Step S4 of FIG. 5 is performed after die bonding.That is, as shown in the wire bonding of FIGS. 10 and 12, inner lead 3 aof lead frame 3 and pad 4 c of a main surface 4 a of semiconductor chip4 are electrically connected with a wire 7. Wire 7 is a gold wire, forexample.

Since coating of the silver plating 5 is performed near the tip of thesurface side of each inner lead 3 a in that case, even if heat treatmentof lead frame 3 with tape 1 (frame baking) was performed and inner lead3 a has oxidized, silver plating 5 portion at that tip has preventedoxidization, therefore can connect wire 7 to this silver plating 5portion.

The molding shown in Step S5 of FIG. 5 is performed after wire bonding.That is, as shown in the molding (resin molding) of FIGS. 11 and 13,semiconductor chip 4 and a plurality of wires 7 are sealed by resinmolding, and a sealed body 6 is formed. Resin for sealing in that caseis a thermosetting epoxy resin etc., for example.

After resin molding, mold baking shown in Step S6 of FIG. 5 beingperformed, bake processing of resin for sealing after hardening isperformed.

Then, plating shown in Step S7 of FIG. 5 is performed. Here, exteriorplating of solder plating etc. is given to a plurality of outer leads 3b projected from sealed body 6.

Lead cut formation shown in Step S8 of FIG. 5 is performed after platingformation. Here, as shown in the cut formation of FIG. 13, cutting andformation of outer lead 3 b are performed. That is, while performingcutting from lead frame 3 of each outer lead 3 b, each outer lead 3 b isbent and formed in the shape of a gull wing, and it becomes assemblycompletion of a QFP (Quad Flat Package) 2.

Next, the semiconductor device of the modification of this Embodiment 1is explained.

The semiconductor device of the modification shown in FIGS. 14 and 15 isa heat radiation type QFP 8, and is a semiconductor device of thestructure where laminated tape member 10 was stuck at the tip of theback side of each inner lead 3 a (the surface of the opposite sideagainst the surface which connects wire 7) via adhesives 1 a.

Since, also in the case of this heat radiation type QFP 8, the defect bycopper migration will occur if each lead which includes inner lead 3 aand outer lead 3 b is formed of copper or a copper alloy, and lowmolecular compounds 1 c (impurities), such as methanol, acetaldehyde, oracetone, are contained in resin of adhesives 1 a, like the manufacturingmethod of the semiconductor device of this Embodiment 1, by heating leadframe 3 at the temperature of 160 to 300° C. (preferably 180 to 300° C.)for a total of more than 2 minutes in the atmosphere which has oxygenafter sticking a tape member 10 on lead frame 3 and before performing aresin molding, the hardening reaction accompanied by oxidizationcrosslinkage 1 d in resin of adhesives 1 a can be promoted, lowmolecular compound 1 c can be volatilized and taken out outside, and thegeneration of migration can be prevented.

As a result, improvement in the reliability of heat radiation type QFP 8can be aimed at.

The semiconductor device of the modification shown in FIGS. 16 and 17 isa TCP (Tape Carrier Package) 13, and is the semiconductor package inwhich semiconductor chip 4 is arranged in a device hole 1 k mostlyformed in the center of tape 1, and a plurality of leads of a copperfoil 1 e arranged around semiconductor chip 4 and pad 4 c ofsemiconductor chip 4 are electrically connected by a bump 11, and towhich the resin molding of semiconductor chip 4, bump 11, and the copperfoil 1 e is performed by sealing part 12.

In tape 1 of this TCP 13, the lead of copper foil 1 e, a wiring part 1 jwhich leads to the lead, and an inner lead 1 g and an outer lead 1 iwhich lead to wiring part 1 j are provided, and inner lead 1 g and outerlead 1 i are connected to a test pad 1 h. While copper foil 1 e andwiring part 1 j are stuck on tape 1 via adhesives 1 a in that case,wiring part 1 j is covered with and insulated by an insulating solderregist 1 f.

A plurality of sprocket holes 1 m are formed in the both-sides part ofthe width direction of tape 1 along with regular intervals. The regioninside a plurality of test pads 1 h provided in both sides serves as auser's area 1 n.

Also in this TCP 13, if wiring part 1 j, inner lead 1 g, and outer lead1 i are formed of copper or a copper alloy, and low molecular compounds1 c (impurities), such as methanol, acetaldehyde, or acetone, arecontained in resin of adhesives 1 a, the defect by copper migration willoccur. Therefore, by heating, after connecting copper foil 1 e, wiringpart 1 j, and tape 1 via adhesives 1 a and before performing a resinmolding, like the manufacturing method of the semiconductor device ofthis Embodiment 1, at the temperature of 160 to 300° C. (preferably 180to 300° C.) for a total of more than 2 minutes in the atmosphere whichhas oxygen, the hardening reaction accompanied by oxidizationcrosslinkage 1 d in resin of adhesives 1 a can be promoted, lowmolecular compound 1 c can be volatilized and taken out outside, and thegeneration of copper migration can be prevented.

As a result, improvement in the reliability of TCP 13 can be aimed at.Adopting the flexible wiring board which stuck the wiring pattern(conductor part) which includes copper or a copper alloy viathermosetting adhesives on a substrate, and applying the manufacturingmethod of the semiconductor device of this Embodiment 1 also when usingthis flexible wiring board in the assembling process of a semiconductordevice, by heating at the temperature of 160 to 300° C. (preferably 180to 300° C.) for a total of more than 2 minutes in the atmosphere whichhas oxygen before performing a resin molding, the generation of coppermigration can be prevented.

Embodiment 2

FIG. 18 is a flow diagram showing an example of the procedure of themanufacturing method of the lead frame of Embodiment 2 of thisinvention;

FIG. 19 is a partial plan view showing an example of the structure ofthe frame after etching in the assembly of the lead frame shown in FIG.18; FIG. 20 is a partial plan view showing an example of the structureof the frame after partial silver plating formation in the assembly ofthe lead frame shown in FIG. 18; and FIG. 21 is a partial plan viewshowing an example of the structure of the frame after taping in theassembly of the lead frame shown in FIG. 18.

This Embodiment 2 explains the procedure of until it ships lead frame 3with tape 1 explained in Embodiment 1 by performing frame baking in alead frame maker. That is, although, in Embodiment 1, the case wherelead frame 3 on which tape 1 was stuck beforehand was prepared by asemiconductor device maker, and where frame baking was performed in asemiconductor device maker after that, was explained, this Embodiment 2explains what performs manufacture of lead frame 3 with tape 1 andfurther performs frame baking in a lead frame maker, and what ships thelead frame 3.

First, as shown in Step S21 of FIG. 18, lead frame 3 is manufactured.That is, a lead pattern is formed by press processing or etchingprocessing, and lead frame 3 which is shown in FIG. 19 and which has aplurality of leads (inner lead 3 a and outer lead 3 b) is formed. Leadframe 3 is formed of copper or a copper alloy.

Then, as shown in FIG. 20, the partial silver plating step which givessilver plating 5 at the tip of each inner lead 3 a is performed. Afterthat, the taping step shown in FIG. 21 is performed. That is, tape 1 isstuck at lead frame 3 about which silver plating 5 is given at the tipof each inner lead 3 a, via adhesives 1 a containing low molecularcompound 1 c (refer to FIG. 1). For example, tape 1 formed in the shapeof a square ring is stuck on each inner lead 3 a along an inner leadsequence. Adhesives 1 a are thermosetting adhesives.

This becomes the completion of the lead frame with a tape shown in StepS21 of FIG. 18.

Then, frame baking shown in Step S22 of FIG. 18 is performed. That is,in the atmosphere which has oxygen, lead frame 3 is heated at thetemperature of 160 to 300° C. (preferably 180 to 300° C.) for a total ofmore than 2 minutes.

Thereby, as for lead frame 3 with a tape, the surface oxidizes anddiscolors.

Then, packing and shipment which are shown in Step S23 of FIG. 18 areperformed.

That is, lead frame 3 with a tape is packed up with the state where itdiscolored, and is shipped.

Thus, by the thing for which manufacture and frame baking of lead frame3 with tape 1 are beforehand performed by a lead frame maker, and leadframe 3 is shipped, what is necessary is just to perform the completelysame assembly as the former in the assembly of a semiconductor device inthe semiconductor device maker supplied in this lead frame 3, andcomparing with the cases where frame baking is performed by asemiconductor device maker, the number of steps can be reduced, and thegeneration of copper migration can also be prevented further.

As mentioned above, although inventions made by these inventors wereconcretely explained based on the embodiment of invention, it cannot beoveremphasized that this invention is not limited to the embodiment ofthe invention, and it can change variously in the range which does notdeviate from the gist.

For example, although the Embodiments 1 and 2 explained the case ofacetaldehyde, methanol, or acetone as low molecular compound 1 c(impurities) volatilized from resin of adhesives 1 a by heating, lowmolecular compound 1 c may not be limited to these substances, and aslong as it is low molecular compound 1 c contained in resin of adhesives1 a, they may be other substances.

Although the Embodiments 1 and 2 explained the case where phenol resinand bismaleimide resin were the main ingredients, in adhesives 1 a,resin used as the main ingredients of adhesives 1 a may be other resin.

This invention is suitable for the manufacturing method of asemiconductor device, and the manufacturing method of a lead frame.

1. A manufacturing method of a semiconductor device assembled using alead frame which has a plurality of leads, comprising the steps of: (a)providing the lead frame comprised of copper or copper alloy, the leadframe having a chip mounting portion, the plurality of leads arrangedaround the chip mounting portion, and a tape steadying each of theplurality of leads, the tape being arranged over the plurality of leadsvia adhesives, wherein the adhesives are mixed adhesives comprisedprimarily of phenol resin and bismaleimide resin, and includingacetaldehyde, methanol or acetone; (b) mounting a semiconductor chip onthe chip mounting portion, the semiconductor chip having a main surface,and a plurality of pads formed on the main surface; (c) electricallyconnecting the plurality of pads of the semiconductor chip with theplurality of leads via a plurality of wires, respectively; (d) forming asealed body for sealing the semiconductor chip, the plurality of wires,and the plurality of leads with a resin such that a part of each of theplurality of leads is exposed from the sealed body; wherein before step(b), the lead frame is heated, at a temperature between 180 degrees and300 degrees for between 2 minutes and 5 minutes, in an atmosphereincluding oxygen.
 2. A manufacturing method of a semiconductor deviceaccording to claim 1, wherein a thickness of the tape is 50 μm.